1. Field of the Invention
The present invention relates to a network management apparatus and method for remotely controlling a state of an IT device, and more particularly, to a network management apparatus and method for remotely controlling a state of an IT device so that Wake-on-LAN (WOL) may be used to change the IT device from an inactive state to an active state over an IP network.
2. Description of Related Art
Generally, an Internet network that is used by IT devices includes layers such as a transport layer, a network layer, a data link layer, a physical layer, etc.
TCP/UDP Protocol is a layer 4 protocol, IP Protocol is a layer 3 protocol, and Ethernet Protocol is a layer 2 protocol.
Each layer has a source node and a destination node, which are entities that perform communication. The source node and the destination node perform communication using a protocol for each layer.
Since communication between any device connected to the Internet and another device on the Internet is connected over layer 3 or higher, the IP protocol needs to be used to connect to the other device on the Internet. In addition, the TCTP/UDP protocol of layer 4 is used depending on a connection scheme.
A device that is connected to a network while being inactivated and configured to receive a remote request, activate a system, and perform main operations and network interoperability can reduce power consumption by using as few resources as possible in an inactive state. Accordingly, the device turns off power provided to a central processing unit (CPU) and most input/output devices.
For a personal computer (PC), Wake-on-LAN (WOL) technology is used to transition from an inactive state to an active state through a local area network (LAN).
The WOL operates by detecting a bit stream with a specific pattern that is input to an LAN port while only the LAN port and a controller are activated.
Since the WOL operates in layer 2, the WOL may be applied to only nodes in the same subnet that is directly connected to layer 2. When the WOL is used at a remote node outside the subnet, the application thereof is difficult because connection with a target device is not guaranteed.
That is, since the target device in the inactive state is not connected with a node outside the subnet over layer 3 or higher, a message transmitted by the external node is not delivered to an inactivated node inside the subnet as long as a separate gateway does not relay the message over layer 2.
Thus, the WOL is applied by broadcasting a WOL message through a gateway having the same subnet to deliver the WOL message to all nodes in the subnet.
According to conventional technology, when a target IT device enters a standby state in which the IT device is waiting for the WOL message, the IT device is inactivated and thus cannot respond to a message received through a network. When a PC is inactivated, the PC may be in a low-power state in which its CPU is stopped to consume minimal power, and power may be partially supplied to an LAN device connected to the network.
In this case, at a predetermined time (several seconds to minutes) after the IT device enters the inactive state, routing information regarding a target device may be deleted from routing information regarding a final router, and then the transmission of an IP network to the target device may be stopped. Also, in order to prevent the routing information from being deleted, there is also a function of permanently maintaining the routing information. However, the function is not widely used due to several reasons such as complexity, security, etc. of network management.